Thermally conductive adhesives and pads are known and used in electronics, lighting, and rechargeable battery assemblies to convey heat away from a heat source and transfer it to a heat sink where it can be dissipated. They are important in the thermal management of devices with semiconductor chips, such as computers, and lighting based on light emitting diodes (LED's), such as overhead lighting and televisions. Conventional products are based on silicone resins that are highly filled with thermally conductive, inorganic particles. Typically, the silicone products are manufactured by a web-based, thermal cure process followed by a batch thermal cure to complete the hydrosilylation chemical reaction.
Greater thermal conductivity of these products is advantageous. One approach to achieve greater thermal conductivity is to add higher levels of thermally conductive, inorganic particles, which can increase the bulk thermal conductivity of the material. However, conformability is another important performance parameter for these materials. The conformability of the thermally conductive material is important since the material may be between surfaces, e.g., a surface of the heat source and a surface of the heat sink, that are irregular, that is not perfectly smooth, or the gap between the two surfaces in which the material is intended to fill not of the same distance throughout. Better conformability can provide better contact between the thermally conductive material and the heat source and heat sink surfaces. Better conformability may speed proper assembly and lower costs. Better conformability can also improve heat transfer at the interfaces of the material with the heat source and heat sink owing to the improved contact between these surfaces. The overall heat transfer rate is dependent on the heat transfer rates at these interfaces and the bulk heat transfer rate through the bulk of the thermally conductive material. Thus, there is a balance between increasing the thermally conductive filler content and maintaining or improving conformability to achieve optimal performance. The resin and resin chemistry can also play an important role in determining conformability.